How long can cannabis be detected in a urine immunoassay for heavy users?

For heavy users of cannabis, urine immunoassays can detect THC metabolites for an extended period due to the accumulation of these substances in fat tissues and their gradual release into the urine. While occasional users might clear metabolites within a few days, heavy users often have significantly longer detection times.

Typically, for someone who consumes cannabis frequently or in large amounts, it can take up to a month or longer for urine tests to return negative results. This is a result of the varying half-lives of THC and its metabolites, where frequent exposure leads to higher concentrations within the body, resulting in longer detection times. The build-up of cannabinoids due to regular use means that metabolites linger in the body, making it possible for them to be detected in urine long after the last use. This reflects the complexity of cannabis metabolism and clearance in individuals with different usage patterns.

Thus, the duration of 1 month aligns with the physiological response seen in heavy cannabis users, marking it as the correct answer.